A Wideband Antenna Calibration Network Using Multi-Layer Coupling Technology

In this brief, the design methodology of an antenna calibration network using multi-layer stripline-slotline coupling is proposed. A multi-layer coupler and a two-stage Wilkinson power divider are designed to ensure the basically stable amplitude-phase characteristics of coupling and achieve the wide frequency band. To minimize phase imbalance, the lengths of channels should be kept equal to the maximum extent possible. In addition, the transmission line conversion structure is applied at each port for integration with the antenna array. Aiming at the problems of signal crosstalk and mutual coupling, the isolated via holes are installed near the lines and metal spacers are placed over the ports. By using the semi-closed structure, part of substrates is dug out to expose the resistor welding position. A semi-closed calibration network in series-parallel-fed is fabricated to verify the design methodology. In 8–16 GHz, the amplitude-phase characteristics are considerable, in which the coupling is 37–44 dB and phase deviation is below 8°. The isolation between ports T1-T16 is greater than 33 dB and voltage standing wave ratio (VSWR) of them is lower than 1.8.